1. Field of the Invention
The present invention relates to a hygiene-compliant display and control device having a front plate as well as a mounting plate and a sealing element which is arranged between front plate and mounting plate.
2. Discussion of Background Information
Machines and systems for the chemical, foodstuffs and pharmaceuticals industry are subject to particularly demanding requirements for hygiene, especially in the case of “open” processes in which the products can come into direct or indirect contact with the manufacturing equipment. Criteria here include resistance to corrosion and a defined surface quality as well as low susceptibility to contamination and cleaning friendliness. This also means a high level of robustness, as along with water jets and cleaning agents, high-pressure cleaners are often used in the necessary frequent cleaning operations. In addition, standards for the nature of the equipment have been developed in order to satisfy these requirements, e.g. protection class IP69K according to EN 60529. Here the number 6 means protection of the electrical equipment against the ingress of solid bodies including dust by complete sealing, and 9K means protection against the ingress of water during high-pressure or steam-jet cleaning.
While appropriately designed electrical cabinets protect many automation components, display and control devices, which are often arranged directly in the workplace, are affected directly by the requirements of this norm and must likewise have the defined protection class, e.g. IP69K. In addition, the materials used must be able to cope with the cleaning chemicals and the temperature, the seals must prevent the ingress of liquids, even under pressure, and the electronics must also be able to withstand the changes in temperature which occur.
Conventional seals are unable to fulfill these requirements and are therefore unsuitable, as a gap in which bacteria and germs and other contamination can settle and accumulate always remains between the components to be sealed, which is inadmissible for the demanding hygiene-compliant requirements.
A seal arrangement, which seals radially inwards between two hollow components, is in turn disclosed in DE 21 37 810 A. Here, an open peripheral gap, in which a sealing element is fitted flush with the inner peripheral surface, is provided radially inwards on a component. However, from this publication, it cannot be seen how the two components are pressed together in order to effect an adequate sealing of the sealing elements.